CVE-2026-2266
MEDIUMCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
2Tags
Description
An improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed DOM-based cross-site scripting via task list content. The task list content extraction logic did not properly re-encode browser-decoded text nodes before rendering, allowing user-supplied HTML to be injected into the page. An authenticated attacker could craft malicious task list items in issues or pull requests to execute arbitrary scripts in the context of another user's browser session. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.18.6 and 3.19.3. This vulnerability was reported via the GitHub Bug Bounty program.
Analysis
DOM-based XSS in GitHub Enterprise Server prior to version 3.20 allows authenticated attackers to execute arbitrary JavaScript in other users' browsers by injecting malicious HTML through task list content in issues and pull requests. The vulnerability stems from improper input neutralization in the task list rendering logic, which fails to re-encode user-supplied content before display. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.
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